Aspects relate generally to integrated circuits. More particularly, various aspects relate to metrology in integrated circuits.
Developing and testing integrated circuit (IC) devices, also referred to as semiconductor devices, involves designing, manufacturing and testing these devices according to desired operating parameters. Quality assurance has been a concern in the development, fabrication and testing of IC devices, but is particularly important as these devices become ever more complex.
Optical proximity correction (OPC) is known in the art as a photolithography enhancement mechanism used to compensate for errors in forming images due to diffraction and/or process effects. OPC helps to compensate for the inability of light to maintain edge placement integrity when used to form shapes, e.g., IC lines, vias, connections, switches, etc. OPC corrects for errors by adding polygons, moving edges, or otherwise modifying a photomask to compensate for the deviation caused by the light used in the subsequent lithography steps. OPC is conventionally performed in a feedback-based process, where a target shape is used to design a mask, which is then modified according to an OPC algorithm, and then a final contour is formed based upon the mask produced by the OPC algorithm. In some cases, the final contour can be produced (either physically or in simulation) in order to test the OPC algorithm and/or drive changes to that algorithm.
While conventional OPC techniques can adequately correct for the effects of features within a level of an IC (intra-level effects), OPC is inadequate to model inter-level effects in an IC.